Narrowing Effect Research Articles

Diminishing effect of a pressure gradient on large-scale rolls of plane Couette flow: A singular value analysis

We investigate the transition from pure Couette flow to Poiseuille flow at Re≈2250 with a focus on the observed disappearance of single-circle coherent structures occupying the whole channel height. According to the DNS study by Gandía-Barberá [], these are accompanied by a change of sign in the Reynolds stress tensor at sufficiently large pressure gradients, although from a deeper theoretical point of view the actual mechanisms for the disappearance of these structures remained completely uncovered. In order to investigate the behavior of these structures theoretically, we use resolvent and structured singular value analysis, with the aforementioned DNS serving as a data basis for comparison, hence simultaneously exploring the capabilities of resolvent and structured singular value analysis in capturing the characteristics of these structures. Through detailed parameter studies, we examine how the pressure gradient influences the length and width of streamwise elongated rolls, noting a shortening and narrowing effect as the flow becomes increasingly pressure driven, and compare these effects to the ones observed in the DNS work. Additional insights into the development of coherent structures are gained, as their wall-normal positions are successfully linked to the occurrence of critical layers within the flow, particularly through structured singular value analysis. The results show that the modified response modes from structured singular value analysis show the best agreement with the DNS observations, suggesting that these analytical approaches can effectively replicate the phenomena otherwise obtained only through costly DNS, and provide deeper insights into the underlying fluid dynamics. Published by the American Physical Society 2025

Stem Cell–Based Therapies via Different Administration Route for Stroke: A Meta-analysis of Comparative Studies

Stroke, a neurological condition from compromised cerebral blood perfusion, remains a major global cause of mortality and disability. Conventional therapies like tissue plasminogen activator are limited by narrow therapeutic windows and potential adverse effects, highlighting the urgency for novel treatments. Stem cell–based therapies, with their neuroprotective and regenerative properties, present a promising yet highly diverse alternative. By conducting literature search and data extraction from the PubMed, Embase, and Cochrane databases, this meta-analysis assessed the clinical efficacy and safety of stem cell–based therapies administered via intravenous (IV) and non-IV routes in 17 studies with stroke patients. Primary outcomes included the National Institute of Health Stroke Scale (NIHSS), Barthel Index (BI), and modified Rankin Scale (mRS), while secondary outcomes included mortality and adverse events. Results demonstrated significant improvements in NIHSS, BI, and mRS scores, particularly in non-IV groups within 6- and 12-month follow-ups, suggesting delayed but enhanced therapeutic efficacy. Mortality was reduced in both IV and non-IV groups, indicating treatment safety. Adverse events, categorized into neurological and systemic complications, showed no significant differences between intervention and control groups, further emphasizing the safety of stem cell therapies. Non-IV routes showed more long-term benefits, potentially due to enhanced cell delivery and integration. These findings demonstrate the potential of stem cell therapies to improve functional recovery and survival in stroke patients, regardless of administration route. However, the delayed response underscores the need for extended follow-up in clinical applications. Further research is required to standardize treatment protocols, optimize cell types and doses, and address patient-specific factors to integrate stem cell therapies into routine clinical practice.

Facile Synthesis of Bandgap-Engineered N-Doped MgO/g-C3N4 Nanocomposites for Enhanced Sunlight-Driven Photocatalytic Degradation of Organic Dyes

This study tests the theory of using a p-n junction to inhibit the recombination of photo-generated electrons and holes in N-MgO/g-C3N4 for the photocatalytic degradation of methylene blue (MB) dye. While the use of n-type semiconductor junctions with g-C3N4 for bandgap narrowing is well-studied in dye degradation, this research explores the innovative application of nitrogen (N)-doped MgO to create a p-type junction with n-type g-C3N4. The N-MgO/g-C3N4 nanocomposites were designed and synthesized to leverage both the bandgap narrowing effect and the formation of a p-n junction. The results demonstrate that these nanocomposites can effectively degrade MB dye under sunlight, achieving over 90% degradation efficiency with a bandgap of 2.63 eV. Under high pH conditions, the degradation efficiency further increased to 94%. The enhanced photocatalytic activity of the N-MgO/g-C3N4 composite is attributed to the formation of a heterojunction, which facilitates efficient separation and transmission of photo-induced charge carriers. This study discusses the detailed mechanism of this enhanced activity, emphasizing the role of the p-n junction in promoting effective charge separation and transfer, thereby improving the photocatalytic performance under sunlight.

Ultranarrow Semiconductor WS2 Nanoribbon Field-Effect Transistors.

Semiconducting transition metal dichalcogenides (TMDs) have attracted significant attention for their potential to develop high-performance, energy-efficient, and nanoscale electronic devices. Despite notable advancements in scaling down the gate and channel length of TMD field-effect transistors (FETs), the fabrication of sub-30 nm narrow channels and devices with atomic-scale edge control still poses challenges. Here, we demonstrate a crystallography-controlled nanostructuring technique to fabricate ultranarrow tungsten disulfide (WS2) nanoribbons as small as sub-10 nm in width. The WS2 nanoribbon junctions having different widths display diodic current-voltage characteristics, providing a way to create and tune nanoscale device properties by controlling the size of the structures. The transport properties of the nanoribbon FETs are primarily governed by narrow channel effects, where the mobility in the narrow channels is limited by edge scattering. Our findings on nanoribbon devices hold potential for developing future-generation nanometer-scale van der Waals semiconductor-based devices and circuits.

Research Progress on Stability of FAPbI3 Perovskite Solar Cells

AbstractThe formamidinium lead iodide (FAPbI3) perovskite has emerged as a promising material for high‐efficiency photovoltaic applications. Although a power conversion efficiency of more than 26% has been achieved, stability issues have hindered its commercial application. In this study, the stability of FAPbI3 under adverse conditions such as humidity, oxygen, ultraviolet light, and temperature fluctuations is systematically reviewed. The known effective strategies for improving stability are discussed. Current studies have shown that technologies such as doping, halide alloying, additive manufacturing engineering, and interface modification have been identified as effective in mitigating phase transitions of FAPbI3 and enhancing environmental durability. Encapsulation technology further improves moisture and heat resistance. Compared with other stabilization strategies, doping and alloying can address the adverse effects of narrowing of the absorption edge. Interface engineering has an essential understanding of the stability mechanism, which will greatly improve the stability problem in the practical application of FAPbI3. This paper also looks forward to the future research directions and development trends.

Escaping the resource curse: does resource dependence reduction mitigate income inequality?

This paper quantifies the impact of resource dependence reduction on income inequality. Using an exogenous shock triggered by China’s sustainable program for resource-based regions and prefecture-level data during 2004–2020, we perform a difference-in-differences estimation and find that reducing resource dependence has a sizable narrowing effect on urban-rural income gap. On average, the sustainable program reduces the gap (as measured by a ratio indicator) by 4.11%, with the effect being more pronounced in regions with initial low institutional quality. Further evidence suggests that the rise of labor-intensive industries and the increased rural investment, which benefit the poor more, help explain the narrowing effect. This paper sheds light on the sustainable development of resource-dependent regions.

41 W, 206 fs regenerative amplifier based on CPA-free amplification of femtosecond pulses

We present a low-cost method to mitigate the gain narrowing effects during regenerative amplification based on a high-repetition-rate, high-power continuously pumped Yb:YAG thin disk regenerative amplifier (RA). By inserting a 1-mm-thick SiO2 plate on a certain position in the RA, the narrowed bandwidth of the amplified spectrum of 3 nm was significantly broadened to a root-mean-square (RMS) bandwidth of 6.9 nm, which reveals the effectiveness of the method. At a repetition rate of 200 kHz, an output power of 41 W was obtained with a compressed pulse duration of 206 fs. The amplifier displayed stability with a root-mean-square power noise as low as 0.46%. The optical resonator remained nearly diffraction-limited beam quality (M2 < 1.35) until the maximum output power.

On tailoring of laser scan approaches for processing of a functionally graded material

ABSTRACT When it comes to machining functionally graded materials like tetragonal zirconia polycrystal-alumina, laser machining has emerged as a prominent technique, surpassing both traditional and non-traditional methods. In spite of its benefits, there are also challenges linked to laser machining of thicker substrates, primarily heat buildup, and loss of energy after many passes. In light of these difficulties, the current research investigates the relative effectiveness of short pulsed laser scan approaches in the processing of tetragonal zirconia polycrystal-alumina. A comparative investigation has been conducted between traditional laser processing and step-down laser processing of thicker tetragonal zirconia polycrystal-alumina, where the time-dependent ablation performance of short pulsed laser processing has been scrutinized with the support of experimental investigations to gain insight into the mechanism of both processes. Experimental results show that step-down laser processing outperforms the traditional laser processing by increasing ablation alongside reducing taperness. Step-down laser processing with scan track modulation effectively reduces the narrowing effect of the Gaussian beam profile by enhancing the machinability of thicker tetragonal zirconia polycrystal-alumina. This indicates its effectiveness in processing thicker substrates; which are substantial for biomedical implants.

Research on comprehensive heat dissipation characteristics of AlSi7Mg TPMS heat sinks manufactured by laser powder bed fusion

The comprehensive heat transfer characteristics of triply periodic minimal surface heat sinks were investigated in this research, and triply periodic minimal surface structures were manufactured by laser powder bed fusion with AlSi7Mg powder. The average surface temperature, thermal resistance, heat transfer coefficient, and specific heat transfer coefficient of heat sinks were tested, and the heat dissipation mechanism was analyzed by finite element thermal flow analysis. The results of thehomogeneous triply periodic minimal surface show that Primitive has the best comprehensive heat transfer performance under forced convection, and Gyroid is the best without forced convection. Compared with homogeneous and gradient triply periodic minimal surfaces, the P-Quadratic ΙΙ structure has the best comprehensive heat transfer performance under forced convection and natural thermal conductivity. Compared with homogeneous Primitive, the average convection heat transfer coefficient of P-Quadratic ΙΙ is increased by 13.44 % ∼ 19.78 %. The finite element thermal flow analysis shows that the narrow tube effect of Bernoulli’s principle and eddy current enhanced the heat transfer performance of Primitive and gradient Primitive.

Digital Inclusive Finance, Rural Loan Availability, and Urban–Rural Income Gap: Evidence from China

Reducing the urban–rural income gap stands as a pivotal factor in attaining sustainable economic development. Policymakers and researchers have focused on whether digital inclusive finance can narrow the urban–rural income gap. Utilizing provincial-level panel data from 31 regions in China, this paper empirically tests the impact of digital inclusive finance on the urban–rural income gap across different areas of China, specifically analyzing the mediation effect of rural loan availability. The findings indicate that (1) the expansion of digital inclusive finance can enhance the inclusiveness of financial services in rural areas and narrow the urban–rural income gap; (2) the effect of digital inclusive finance on the urban–rural income gap exhibits regional heterogeneity; (3) the rural loan availability has a mediation effect on the urban–rural income gap, but its growth will weaken the narrowing effect of digital inclusive finance on urban–rural income gap; and (4) the reduction in the urban–rural income gap attributable to digital inclusive finance exhibits a nonlinear relationship with the level of urbanization. This paper recommends guiding the digital transformation of rural financial institutions and enhancing farmers’ financial literacy to increase the availability of loans in rural areas. Furthermore, implementing region-specific policies and regulations could effectively narrow the urban–rural income gap.

Progress on clay swelling inhibitors: a comprehensive review

Relevance. It is known that swelling of a well wall due to the presence of water negatively affects drilling operations, causing a significant increase in their material costs. The use of various inhibitors prevents this effect and the drilling mud reacting on wellbore narrowing. In this sense, the problems of developing polymer, amino-, ionic liquid and shale inhibitors of surfactants considered in the article are very relevant and of practical interest to oil engineers in terms of the prospects for fundamental and applied researches of these issues. Aim. To study the possibilities of existing approaches and methods that determine the characteristics of the main clay swelling inhibitors, the regularities of changes in the properties of traditional and non-traditional clay materials, as well as the mechanisms of clay swelling with the identification of the most characteristic group of these inhibitors. Object. Processes of minimizing the effect of wall narrowing as a result of exposure to inhibitors. Methods. Systematic, critical and comprehensive analysis of modern data on clay swelling inhibition in the field of drilling muds. Results. The authors have carried out the detailed analysis of clay swelling. The paper discusses the characteristics of inhibitors required to prevent swelling, in the structure of which nitrogen and ionic liquids are contained. It is noted that a high-quality clay swelling inhibitor should include in its base a water-soluble bulk molecule with a distinct hydrophobic and hydrophilic structure; have characteristics, which allow replacing the hydrated cations of the intermediate layer with some hydrophobic cations, such as ammonium ions instead of sodium ions; differ in the ability to disperse multiple cations well. It was found that functional groups that support inhibitor binding to the siloxane groups of the clay are able to significantly expand clay swelling.

Automated CT-based decoupling of the effects of airway narrowing and wall thinning on airway counts in chronic obstructive pulmonary disease.

We examine pathways of airway alteration due to wall thinning, narrowing, and obliteration in chronic obstructive pulmonary disease (COPD) using CT-derived airway metrics. Ex-smokers (N = 649; age mean ± std: 69 ± 6 years; 52% male) from the COPDGene Iowa cohort (September 2013-July 2017) were studied. Total airway count (TAC), peripheral TAC beyond 7th generation (TACp), and airway wall thickness (WT) were computed from chest CT scans using previously validated automated methods. Causal relationships among demographic, smoking, spirometry, COPD severity, airway counts, WT, and scanner variables were analysed using causal inference techniques including direct acyclic graphs to assess multi-pathway alterations of airways in COPD. TAC, TACp, and WT were significantly lower (P < .0001) in mild, moderate, and severe COPD compared to the preserved lung function group. TAC (TACp) losses attributed to narrowing and obliteration of small airways were 4.59%, 13.29%, and 32.58% (4.64%, 17.82%, and 45.51%) in mild, moderate, and severe COPD, while the losses attributed to wall thinning were 8.24%, 17.01%, and 22.95% (12.79%, 25.66%, and 33.95%) in respective groups. Different pathways of airway alteration in COPD are observed using CT-derived automated airway metrics. Wall thinning is a dominant contributor to both TAC and TACp loss in mild and moderate COPD while narrowing and obliteration of small airways is dominant in severe COPD. This automated CT-based study shows that wall thinning dominates airway alteration in mild and moderate COPD while narrowing and obliteration of small airways leads the alteration process in severe COPD.

Numerical Simulation and Parameter Optimization of a New Slant Insertion-Opening Combination Sand Fence

This paper presents a new slant insertion-opening combination sand fence designed to reduce the hazards of traditional railway sand damage along the line. This new fence aims to decrease the disturbance caused by lateral wind on the high-speed railway and minimize the deposition of track sand particles. Numerical modeling and wind tunnel testing were employed to examine the structure’s defensive capabilities. Using the computational fluid dynamics (CFD) method and the Eulerian–Eulerian two-fluid model, the wind protection effect and airflow characteristics of the new sand fence with different slant insertion angles and spacings were simulated, and the optimal configuration parameters were selected. The study found that the new mechanical sand fence exhibits similar performance to the traditional sand fence. Since there is a “narrow tube effect”, the leeward side of the inclined plate generates a local high-speed airflow zone. In the top acceleration zone, the new mechanical sand fence efficiently lowers air velocity, thereby enhancing its protective capabilities. Moreover, the optimal protective performance of the new mechanical sand fence is achieved with an inclination angle of 15°, with improved protection observed as the angle increases. Additionally, the protective performance of double rows of these fences is influenced by the spacing between them. Increasing the distance between the two rows enhances protective performance, with the optimal protection achieved at a spacing of 25H. Beyond this distance, protective performance decreases.

Lithium’s renaissance: From psychiatric staple to multifaceted medical marvel

Abstract: Lithium, long established as a cornerstone in the treatment of bipolar disorder, has recently emerged as a potential therapeutic agent across a broad spectrum of medical fields. This narrative review examines the expanding role of lithium in contemporary medicine, highlighting its transition from a psychiatric staple to a versatile therapeutic tool. The objective of the study was to synthesize and critically evaluate recent literature on lithium’s applications beyond psychiatry, focusing on its mechanisms of action, therapeutic potential, and challenges in various medical domains. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science databases, focusing on peer-reviewed articles published within the last 5 years. Keywords included “lithium” combined with terms such as “neuroprotection,” “cancer,” “stem cells,” “viral infections,” and “aging.” Case studies, clinical trials, systematic reviews, and meta-analyses were included to provide a broad perspective on lithium’s emerging roles. Recent studies have revealed lithium’s potential in several key areas: neuroprotection in neurodegenerative disorders, cancer therapy enhancement, stem cell mobilization for regenerative medicine, antiviral properties, cardioprotection against ischemia-reperfusion injury, circadian rhythm regulation, and potential effects on longevity and healthy aging. Lithium’s renaissance in medical research reveals its potential as a multifaceted therapeutic agent. While challenges remain, including its narrow therapeutic index and side effect profile, ongoing research into novel delivery methods and personalized medicine approaches may optimize its use. The expanding applications of lithium underscore the need for continued investigation to fully harness its therapeutic potential across various medical disciplines.

Infant sensitivity to mismatches between same/other-race faces and native/non-native speech

Perceptual narrowing typically occurs around 6 months of age, and drastically changes an infant’s perception of stimuli such as faces or spoken language according to the frequency with which the infant encounters them. It has already been well established that perceptual narrowing improves the sensitivity of infants to frequently encountered stimuli such as same-race faces and their native language while reducing their sensitivity to other-race faces and non-native languages. However, the effect of perceptual narrowing on the combined perception of face and language stimuli is not well understood. Therefore, to investigate the changes in the sensitivity of infants to matches and mismatches between faces and speech which might occur in the course of perceptual narrowing, we tested 3- and 9-month-old German infants using German faces and German spoken sentences which would be familiar to the infants, as well as completely unfamiliar Chinese faces and French spoken sentences. The infants were tested using an intermodal association paradigm, whereby each infant saw sequences of German or Chinese faces, interspersed with German or French spoken sentences. We analyzed the total looking time of infants in conditions where the faces and spoken sentences were congruent (either both familiar, or both unfamiliar), versus incongruent conditions where only the faces or only the sentences were familiar. We found that while the 9-month-olds looked for similar durations in congruent versus incongruent conditions, the 3-month-olds looked significantly longer during congruent conditions versus incongruent conditions, indicating a greater attentiveness to face-speech matches and mismatches prior to the onset of perceptual narrowing.

Unsteady Aerodynamic Forces of Tandem Flapping Wings with Different Forewing Kinematics.

Dragonflies can independently control the movement of their forewing and hindwing to achieve the desired flight. In comparison with previous studies that mostly considered the same kinematics of the fore- and hindwings, this paper focuses on the aerodynamic interference of three-dimensional tandem flapping wings when the forewing kinematics is different from that of the hindwing. The effects of flapping amplitude (Φ1), flapping mean angle (ϕ1¯), and pitch rotation duration (Δtr1) of the forewing, together with wing spacing (L) are examined numerically. The results show that Φ1 and ϕ1¯ have a significant effect on the aerodynamic forces of the individual and tandem systems, but Δtr1 has little effect. At a small L, a smaller Φ1, or larger ϕ1¯ of the forewing can increase the overall aerodynamic force, but at a large L, smaller Φ1 or larger ϕ1¯ can actually decrease the force. The flow field analysis shows that Φ1 and ϕ1¯ primarily alter the extent of the impact of the previously revealed narrow channel effect, downwash effect, and wake capture effect, thereby affecting force generation. These findings may provide a direction for designing the performance of tandem flapping wing micro-air vehicles by controlling forewing kinematics.

Can China’s belt and road initiative narrow the income gap between the Han people and ethnic minority residents? Evidence from a regression discontinuity design

The Belt and Road (B&R) policy is a region-oriented economic policy implemented by the Chinese government since 2010, involving the largest population and covering the largest area in the world. Whether it can significantly narrow the income gap between Han and ethnic minority residents has not been investigated in the literature. To avoid endogenous problems in the model, we used the spatial breakpoint regression method to investigate 2,037 county-level administrative regions in China from 2014 to 2021 and empirically evaluated the impact of the policy on the income gap between Han and ethnic minority residents. Results show that, compared to the counties without B&R policy, the average income gap between minority counties with B&R and Han has increased by 1.468–1.518 times, which was nearly 1.3 times the sample mean of survey data, indicating that the income gap has been widened significantly by B&R. However, the policy has a narrowing effect on the income gap between minorities and Han in the 20% sample with the widest income gap between minorities and Han. From the dynamic effect of years, with the effect of B&R, the income gap between minorities and Han is an inverted U-shaped curve, first increasing and then decreasing.

The impact of pensions on the income gap among the elderly: the case of Taiwan’s National Pension

ABSTRACT In most countries, first-pillar public pension systems provide comprehensive coverage for all citizens. By contrast, Taiwan’s unique National Pension (NP) is a compulsory, defined-benefit pension insurance that covers citizens excluded from occupation-based social insurance. As such, the NP inevitably includes disadvantaged citizens in its coverage. Using NP administrative data to link labour insurance, social welfare allowance, and income tax, we find that the NP narrows the pension benefit gap between the disadvantaged and the non-disadvantaged. The narrowing effect is stronger for the younger than for the older generation. Furthermore, the NP enhances pension benefits for women more than for men, thereby narrowing the difference in pension benefits between the sexes. As expected, the NP is more important for low-income citizens than for their wealthy counterparts.

Uncoupling the CRMP2-CaV2.2 Interaction Reduces Pain-Like Behavior in a Preclinical Joint-Pain Model

Osteoarthritis (OA) represents a significant pain challenge globally, as current treatments are limited and come with substantial and adverse side effects. Voltage-gated calcium channels have proved to be pharmacologically effective targets, with multiple Food and Drug Administration-approved CaV2.2 modulators available for the treatment of pain. Although effective, drugs targeting CaV2.2 are complicated by the same obstacles facing other pain therapeutics—invasive routes of administration, narrow therapeutic windows, side effects, and addiction potential. We have identified a key regulator of CaV2.2 channels, collapsin response mediator protein 2, that allows us to indirectly regulate CaV2.2 expression and function. We previously developed a peptidomimetic modulator of collapsin response mediator protein 2, CBD3063, that effectively reverses neuropathic and inflammatory pain without negative side effects by reducing membrane expression of CaV2.2. The potent analgesic properties of CBD3063, combined with the lack of negative side effects, prompted us to assess the efficacy of CBD3063 in a rodent model of OA pain. Here, we demonstrate the intraperitoneal administration of CBD3063 alleviates both evoked and nonevoked behavioral hallmarks of OA pain. Further, we reveal that CBD3063 reduces OA-induced increased neural activity in the parabrachial nucleus, a key supraspinal site modulating the pain experience. Together, these studies suggest that CBD3063 is an effective analgesic for OA pain. PerspectiveDespite the high prevalence of OA pain worldwide, current treatment options remain limited. We demonstrate that CBD3063-mediated disruption of the CaV2.2-collapsin response mediator protein 2 interaction alleviates pain in a preclinical joint pain model, providing a promising basis for the development of new OA pain treatments.

Theory and quantum dynamics simulations of exciton-polariton motional narrowing.

The motional narrowing effect has been extensively studied for cavity exciton-polariton systems in recent decades both experimentally and theoretically, which is featured by (1) the subaverage behavior and (2) the asymmetric linewidths for the upper polariton and the lower polariton. However, a minimal theoretical model that is clear and adequate to address all these effects as well as the linewidth scaling relations remains missing. In this work, based on the single mode 1D Holstein-Tavis-Cummings (HTC) model, we studied the motional narrowing effect of the polariton linear absorption spectra via both semi-analytic derivations and numerically exact quantum dynamics simulations using the hierarchical equations of motion approach. The results reveal that under collective light-matter coupling between a cavity mode and N molecules, the polariton linewidth scales as 1/N under the slow limit, while scales as 1/N under the fast limit, due to the polaron decoupling effect. Furthermore, by varying the detunings, the polariton linewidths exhibit significant motional narrowing, covering both characters mentioned above. Our analytic linewidth expressions [Eqs. (34) and (35)] agree well with the numerical exact simulations in all the parameter regimes we explored. These results indicate that the physics of motional narrowing is adequately accounted for by the single-mode 1D HTC model. We envision that both the numerical results and the analytic polariton linewidths expression presented in this work will offer great theoretical value for providing a better understanding of the exciton-polariton motional narrowing based on the HTC model.